This invention relates to a multi-function revolving door, and more particularly to a revolving door which is capable of regular use as well as use for emergency exit purposes.
In order to allow a steady traffic of persons walking in and out of buildings, such as shopping centeers, hospitals, airports, etc., it is necessary to have door arrangements in order to keep the indoor climate under control. Three systems are available: air curtains, automatic sliding or swing doors, and revolving doors. These solutions are good from a technical point of view, but the known products available all have serious drawbacks.
Air curtains are extremely energy consuming and therefore costly to operate. In a cold climate, it is impossible to suppress a draft in town blocks caused by the tall, relatively warm air in the building, creating what is known as the chimney effect. Furthermore, air curtains cannot control the drifting-in of dust. Also, noise passes unhindered into the building.
Automatic sliding or swing doors are less expensive to operate than air curtains, but they let as much as up to ten times the quantity of cold air into the building (or air conditioned cold air out) as the quantity ventilated by revolving doors. Dust and noise inlet are also unsatisfactorily controlled, especially during peak hours.
The present state of art respecting revolving doors is exemplified by U.S. Pat. Nos. 906,175; 1,030,266; 1,303,988; 2,523,980; 3,782,035; 3,020,038; 3,497,997; and 3,766,686.
Revolving doors constitute the one construction ensuring a permanent seal between the outdoor and indoor air masses. They provide the buildings with excellent noise, dust and draft control, and very low energy loss, thus reducing operation costs, and costs of maintenance.
Revolving doors of known construction do not provide buildings with an emergency exit capacity of sufficient volume independent of the position of the revolving body, and are either (1) dependent on a turning of the revolving body to one of a limited number of positions before folding of the door leaves results in a free passage or (2) are capable of establishing only one passageway. The first arrangement is not practical for a panicky crown and thus not acceptable to the public authorities, and the second arrangement does not provide adequate escape volume.
Revolving doors of known design have the upper bearing for the revolving body supported above said body. They are in this respect dependent on the adjacent structure in the building or otherwise have a supporting structure integrated into the door canopy.
Traffic in and out of public buildings includes persons with shopping carts, baby carriages, and persons in wheel chairs, or otherwise handicapped. The capacity to let such "traffic units" pass can only be provided by revolving doors with large diameters, i.e., diameters exceeding two meters and often more than three meters. These large rotating bodies are relatively heavy constructions. The rotation of the revolving door, therefore, is often motorized to enable handicapped persons, and persons otherwise unable to push the door leaves, to pass.
The motor drive for the rotating body of a revolving door requires either space in the building structure below the door floor, or space and supporting structure in the superjacent building parts. The hard push caused by a relatively fast moving heavy door leaf catching up with a slowly walking person, or the more violent "bumps" executed by a door leaf hitting an immobile person or lost item, are technical problems not satisfactorily resolved until now.